Induction heater



1- F. BLACK INDUCTION HEATER Filed July 20, 1940 Inventor La. wrence 5/46/( A iiorney Patented Dec. 9,1941

UNITED STATES PATENT OFFICE INDUCTION nns'rna Lawrence F. Black, Washington, D. 0.

Application July 20,1940, Serial No. 346,634

6Claims.

My invention relates to improvements in electric fluid heaters of the induction type, and the primary object of the invention is to provide increased efficiency and practicability in such heaters and render the same suitable for general application in the heating and circulating of both liquids and gases.

Other important objects and advantages of my invention will be apparent from a reading of the following description and the appended drawing wherein a preferred embodiment of the invention is shown for illustrative purposes.

In the drawing:

Figure 1 is a general sectional and perspective schematic view showing an arrangement in accordance with the present invention and a diagram of its electrical connections.

Figure 2 is a fragmentary enlarged transverse vertical sectional view taken through the annular conduit.

Figure 3 is a fragmentary transverse vertical sectional view taken through Figure 2.

Referring in detail to the drawing, the numeral 5 generally designates a closed core or shell-type transformer having a primary winding 6 on the center leg 1, one end of this winding being connected to the movable element 8, such as an arm or slider, of a voltage regulator or current supply transformer which is generally designated 9, whose primary III has its ends connected to the two sides of a suitable source of current. The remaining end of the primary winding 6 of the transformer 5 is connected to one end-of the secondary ll of the supply transformer 8. A voltmeter I2, graduated to show degrees either Fahrenheit or centigrade and shunted between the ends of the primary winding 6, between this winding and the transformer 9.

The secondary of the shell-type transformer consists of an'annular conduit II which has one vertical conduit l4 rising from its top and passing through the bottom of the liquid or gas container ii to an elevated point designated l6, below the liquid or gas level is. The annular conduit II has a second vertical conduit I! depending from its bottom for a substantial distance and then brought upwardly to open through the bottom of the said container at It.

The annular conduit is formed of non-magnetizable material of low electrical conductivity such as non-magnetic stainless steel or plastic material, and the like, and although not necessarily, the vertical conduits I4 and II can be of the same material as the annular conduit. Within the annular conduit which is preferably substantially cylindrical in cross section is a round cross section copper or silver ring 20 which is normally concentrically spaced from th walls of the annular conduit as shown in Figures 2 and 3. The electrical mutual repulsion of the ring 2|! an the annular conduit l3 and the movement of the fluid therethrough floats the ring in concentric relation to the conduit II.

The annular conduit I3 concentrically surrounds an intermediate portion of the middle arm I of the transformer 5 and the primary core winding 5 thereon, so that both the annular conduit and the copper or silver ring have currents induced therein and become heated due to passage of the current induced therein. Because of the greater contact existing between the liquid or gas and the annular conduit l3 and the ring 20 a quicker and larger transfer of heat to the liquid or gas takes place. The cold fluid sinking of its own accord down the conduit I! from the lower part of the container Ii is rapidly heated and to a high temperature. Because of its tendency to rise the hot water circulates upwardly through the conduit H to discharge into the upper part of the body of fluid in the container I 5. Cooling and consequent subsidence of the fluid toward the lower part of the container in cooperation with the rise of the warmer fluid produces substantially constant circulation of the fluid during energization of the transformer 5.

For heating effect the present device does not depend principally upon the generation of heat due to the resistance of the annular conduit l3 and inner ring 20 to the passage of the induced currents therein. Dependence for heating effect is placed rather on the high amperages of the induced currents in the said elements acting on the fluid therein, the energizing current for the transformer being of relatively low voltage.

Although I have shown and described a preferred embodiment of my invention, it is to be understood that I do not wish to limit the application of my invention thereto except as may be required by the scope of the subjoined claims.

What is claimed is:

1. A fluid heater of the character described, said heater comprising a low voltage source, a shell type transformer having its primary winding connected to said source, said transformer having a horizontal E-shaped closed core with said primary winding on the middle armof said core, a high resistance, non-magnetizable annular conduit circumposed on said middle arm and encircling said primary winding with the remaining arms of said core lying outside of the 2. A fluid heater of the character described, 7

said heater comprising a low voltage source, a shell type transformer having its primary winding connected to said source, said transformer having a horizontal E-shaped closed core with said primary winding on the middle arm of said core, a non-magnetizable annular conduit circumposed on said middle arm and encircling said primary winding with the remaining arms of said core lying outside of the edges of said annular conduit, a fluid container supported at a level above said annular conduit, a first vertical conduit rising from the top of said annular conduit and opening into the upper part of the body of fluid in the container, a second vertical conduit depending from the bottom of said annular conduit and having its upper end opening into the lower part of the body of fluid in said container, an inner metallic ring in said annular conduit, said ring being of low resistance metal core with a primary winding thereon, an annular v water conduit surrounding said primary winding. a water container, pipes leading from spaced points of said water conduit and communicating with said water container, a metallic ring in said annular conduit and normally spaced from the interior walls of said annular conduit.

4. A fluid heater oi the character described, said heater comprising a transformer having a core with a primary winding thereon, an annular water conduit surrounding said primary winding, a water container, pipes leading from spaced points of said water conduit and communicating with said water container, a metallic ring in said annular conduit and normally spaced from the interior walls of said annular conduit, said ring being of relatively low resistance to the passage of electricity.

5. A fluid heater of the character described, said heater comprising a transformer having a core with a primary winding thereon, an annular water conduit surrounding said primary winding, a water container, pipes leading from spaced points of said water conduit and communicating with said water container, a metallic r;ng in said annular conduit and normally spaced from the interior walls of said annular conduit, said ring being of 'round cross section.

6. A fluid heater of the character described, said heater comprising a transformer having a core with a primary winding thereon, an annular water conduit surrounding said primary winding, a water container, .pipes leading from spaced points of said water conduit and communicating with said water container, a metallic ring in said annular conduit and normally spaced from the interior walls of said annular conduit, said ring being of round cross section, and formed of one of a group consisting of copper and silver.

' LAWRENCE F. BLACK. 

